A headlight disclosed in Japanese Patent Application Laid-Open No. 2005-108554 is configured to allow switching between a high beam mode and a low beam mode. A first semiconductor light emitting element is mounted on the upper surface of a thin plate-shaped travel blocking member in this headlight. Furthermore, a second semiconductor light emitting element is mounted on the lower surface of the travel blocking member. A projection lens is arranged in front of the travel blocking member and has a focal point that is set at or near the edge of the forward end of the travel blocking member. A first reflector is provided on the periphery of the first semiconductor light emitting element and a second reflector is provided on the periphery of the semiconductor light emitting element.
When the headlight is set to a low beam mode, only the first semiconductor light emitting element can emit light beams and when the headlight is set to the high beam mode, both of the semiconductor light emitting elements can emit light beams.
When the first semiconductor light emitting element emits light beams, the light beams emitted from the first semiconductor light emitting element are reflected by the first reflector in the forward direction to be converged close to the focal point of the projection lens. In addition to this, part of the reflected light beams is blocked by the travel blocking member. Because of this, the area being illuminated falls below the horizontal plane thereby controlling the occurrence of glare toward oncoming vehicles.
In contrast, when the second semiconductor light emitting element emits light beams, the light beams emitted from the second semiconductor light emitting element are reflected by the second reflector in the forward direction to be converged close to the focal point of the projection lens. In addition to this, part of the reflected light beams is blocked by the travel blocking member. Because of this, the area being illuminated rises above the horizontal plane and this area being illuminated by the second semiconductor light emitting element is combined with the area being illuminated by the first semiconductor light emitting element, and accordingly, the headlight can be in the high beam mode. Although reflecting surfaces are provided on the upper surface and the lower surface of the travel blocking member, even if a reflecting surface is provided, each of the light distribution patterns only will become brighter regardless of whether the area being illuminated becomes larger.
Although this is the case, because both of the semiconductor light emitting elements emit light beams when the headlight disclosed in Japanese Patent Application Laid-Open No. 2005-108554 (or its corresponding U.S. Pat. No. 7,156,544) is in the high beam mode, the power consumption of the headlight when set to the high beam mode is double the power consumption of the headlight when set to the low beam mode, thereby increasing the power consumption of the headlight when set to the high beam mode.
In addition, because the area being illuminated when the headlight is set to the high beam mode is formed by combining the area being illuminated by the first semiconductor light emitting element with the area being illuminated by the second semiconductor light emitting element, the region of brightness where the area being illuminated by the first semiconductor light emitting element and the area being illuminated by the second semiconductor light emitting element are overlapped becomes much brighter than other regions of brightness. For this reason, the association of the illumination distribution when the headlight is set to the high beam mode can deteriorate and cause uneven brightness.